A disk device includes a main control unit controlling the operation of a controlled object on the basis of an error signal calculated from a target signal of the controlled object and an observation signal of the controlled object, a repetitive control unit sampling the error signal with a sampling clock pulse to obtain a repetitive signal component generated in synchronization with rotation of the disk medium from the sampled error signal, a sampling clock generation unit generating the sampling clock pulse and resetting a timing at which the sampling clock pulse is generated in accordance with a rotation detecting pulse and a sampling clock limit unit limiting generation of the sampling clock pulse at a timing immediately before generation of the rotation detecting pulse.